From 0182c7147a1d40ba4b02dc3efc47865d39ba30d7 Mon Sep 17 00:00:00 2001
From: Abdelhakim Qbaich <abdelhakim@qbaich.com>
Date: Mon, 20 Apr 2020 20:58:59 -0400
Subject: [PATCH] Support library for Gambit Scheme

---
 support/gambit/support.scm | 236 +++++++++++++++++++++++++++++++++++++
 1 file changed, 236 insertions(+)
 create mode 100644 support/gambit/support.scm

diff --git a/support/gambit/support.scm b/support/gambit/support.scm
new file mode 100644
index 0000000..81ca72a
--- /dev/null
+++ b/support/gambit/support.scm
@@ -0,0 +1,236 @@
+(define (blodwen-read-args desc)
+  (case (vector-ref desc 0)
+    ((0) '())
+    ((1) (cons (vector-ref desc 2)
+               (blodwen-read-args (vector-ref desc 3))))))
+
+(define (b+ x y bits) (remainder (+ x y) (arithmetic-shift 1 bits)))
+(define (b- x y bits) (remainder (- x y) (arithmetic-shift 1 bits)))
+(define (b* x y bits) (remainder (* x y) (arithmetic-shift 1 bits)))
+(define (b/ x y bits) (remainder (exact-floor (/ x y)) (arithmetic-shift 1 bits)))
+
+(define blodwen-and bitwise-and)
+(define blodwen-or bitwise-ior)
+(define blodwen-xor bitwise-xor)
+(define blodwen-shl arithmetic-shift)
+(define (blodwen-shr x y) (arithmetic-shift x (- y)))
+
+(define exact-floor ##flonum->fixnum) ; XXX
+
+(define (cast-string-double x)
+  (define (cast-num x)
+    (if (number? x) x 0))
+  (define (destroy-prefix x)
+    (if (or (equal? x "") (char=? (string-ref x 0) #\#)) "" x))
+  (cast-num (string->number (destroy-prefix x))))
+
+(define (cast-string-int x)
+  (exact-floor (cast-string-double x)))
+
+(define (string-cons x y)
+  (string-append (string x) y))
+
+(define (string-reverse x)
+  (list->string (reverse! (string->list x))))
+
+(define (string-substr off len s)
+  (let* ((start (max 0 off))
+         (end (min (+ start (max 0 len))
+                   (string-length s))))
+    (substring s start end)))
+
+(define (get-tag x)
+  (vector-ref x 0))
+
+;; These two are only used in this file
+(define (either-left x) (vector 0 x))
+(define (either-right x) (vector 1 x))
+
+(define (blodwen-error-quit msg)
+  (display msg)
+  (newline)
+  (exit 1))
+
+;; Buffers
+
+(define blodwen-new-buffer make-bytevector)
+(define blodwen-buffer-size bytevector-length)
+
+(define blodwen-buffer-setbyte u8vector-set!)
+(define blodwen-buffer-getbyte u8vector-ref)
+
+(define blodwen-buffer-setint s32vector-set!)
+(define blodwen-buffer-getint s32vector-ref)
+
+(define blodwen-buffer-setdouble f64vector-set!)
+(define blodwen-buffer-getdouble f64vector-ref)
+
+(define (blodwen-stringbytelen str)
+  (bytevector-length (string->utf8 str)))
+
+(define (blodwen-buffer-setstring buf loc val)
+  (let* ((strvec (string->utf8 val))
+         (len (bytevector-length strvec)))
+    (bytevector-copy! strvec 0 buf loc len)))
+
+(define (blodwen-buffer-getstring buf loc len)
+  (let ((newvec (make-bytevector len)))
+    (bytevector-copy! buf loc newvec 0 len)
+    (utf8->string newvec)))
+
+(define (blodwen-buffer-copydata buf start len dest loc)
+  (bytevector-copy! buf start dest loc len))
+
+(define (blodwen-readbuffer-bytes h buf loc max)
+  (with-exception-catcher
+    (lambda (e) -1)
+    (lambda () (read-subu8vector buf loc (+ loc max) h))))
+
+(define (blodwen-readbuffer h)
+  (with-exception-catcher
+    (lambda (e) #u8())
+    (lambda () (list->u8vector (read-all h read-u8)))))
+
+(define (blodwen-writebuffer h buf loc max)
+  (with-exception-catcher
+    (lambda (e) -1)
+    (lambda () (write-subu8vector buf loc (+ loc max) h) max)))
+
+;; Files
+
+;; If the file operation raises an error, catch it and return an appropriate
+;; error code
+(define (blodwen-file-op op)
+  ;; All the file operations are implemented as primitives which return
+  ;; Either Int x, where the Int is an error code:
+  (define (blodwen-error-code x)
+    (either-left
+      ;; TODO Equivalent of i/o-read-error? and i/o-write-error?
+      ;; TODO Uncomment on the next release (> 4.9.3) of Gambit
+      (cond ((no-such-file-or-directory-exception? x) 3)
+            ; ((permission-denied-exception? x) 4)
+            ; ((file-exists-exception? x) 5)
+            (else 255))))
+  (with-exception-catcher
+    blodwen-error-code
+    (lambda () (either-right (op)))))
+
+#|
+(define (blodwen-get-n n p)
+  (if (input-port? p) (read-string n p) ""))
+|#
+
+(define (blodwen-putstring p s)
+  (if (output-port? p) (write-string s p))
+  0)
+
+(define (blodwen-open file mode bin)
+  (define settings
+    (if (fx= bin 1)
+        `(path: ,file buffering: line)
+        `(path: ,file buffering: line char-encoding: UTF-8)))
+  (cond
+    ((string=? mode "r") (open-input-file settings))
+    ((string=? mode "w") (open-output-file settings))
+    ((string=? mode "wx") (open-output-file (append settings '(create: #t))))
+    ((string=? mode "a") (open-output-file (append settings '(append: #t))))
+    ((string=? mode "r+") (open-file settings))
+    ((string=? mode "w+") (open-file (append settings '(create: maybe truncate: #t))))
+    ((string=? mode "w+x") (open-file (append settings '(create: #t truncate: #t))))
+    ((string=? mode "a+") (open-file (append settings '(create: maybe append: #t))))
+    (else (raise 'i/o-error)))) ; XXX
+
+(define (blodwen-close-port p)
+  (if (port? p) (close-port p)))
+
+(define (blodwen-get-line p)
+  (if (input-port? p)
+      (let ((str (read-line p #\newline #t)))
+        (if (eof-object? str) "" str))
+      ""))
+
+(define (blodwen-get-char p)
+  (if (input-port? p)
+      (let ((chr (read-char p)))
+        (if (eof-object? chr) #\nul chr))
+      #\nul))
+
+(define (blodwen-file-modified-time p) ; XXX
+  (exact-floor (time->seconds (file-last-modification-time (##port-name p)))))
+
+#|
+(define (blodwen-file-size p) ; XXX
+  (file-size (##port-name p)))
+|#
+
+(define (blodwen-eof p)
+  (if (eof-object? (peek-char p)) 1 0))
+
+;; Directories
+
+(define blodwen-current-directory current-directory)
+
+(define (blodwen-change-directory dir)
+  (with-exception-catcher
+    (lambda (e) 0)
+    (lambda () (current-directory dir) 1)))
+
+(define (blodwen-create-directory dir)
+  (blodwen-file-op (lambda () (create-directory dir) 0)))
+
+(define (blodwen-open-directory dir)
+  (blodwen-file-op (lambda () (open-directory dir))))
+
+(define blodwen-close-directory close-input-port)
+
+(define (blodwen-next-dir-entry dir)
+  (let ((e (read dir)))
+    (if (eof-object? e)
+        (either-left 255)
+        (either-right e))))
+
+;; Threads
+
+(define (blodwen-thread p)
+  (thread-start! (make-thread (lambda () (p #(0))))))
+
+(define (blodwen-get-thread-data)
+  (let ((data (thread-specific (current-thread))))
+    (if (eq? data #!void) #f data)))
+
+(define (blodwen-set-thread-data a)
+  (thread-specific-set! (current-thread) a))
+
+(define blodwen-mutex make-mutex)
+(define blodwen-lock mutex-lock!)
+(define blodwen-unlock mutex-unlock!)
+(define blodwen-thisthread current-thread)
+
+(define blodwen-condition make-condition-variable)
+(define blodwen-condition-signal condition-variable-signal!)
+(define blodwen-condition-broadcast condition-variable-broadcast!)
+(define (blodwen-condition-wait c m)
+  (mutex-unlock! m c)
+  (mutex-lock! m))
+(define (blodwen-condition-wait-timeout c m t) ; XXX
+  (mutex-unlock! m c t)
+  (mutex-lock! m))
+
+(define blodwen-sleep thread-sleep!)
+(define (blodwen-usleep s) (thread-sleep! (/ s 1e6)))
+
+(define (blodwen-time)
+  (exact-floor (time->seconds (current-time))))
+
+(define (blodwen-args)
+  (define (blodwen-build-args args)
+    (if (null? args)
+        #(0) ; Prelude.List
+        (vector 1 (car args) (blodwen-build-args (cdr args)))))
+  (blodwen-build-args (cdr (command-line))))
+
+(define (blodwen-hasenv var)
+  (if (getenv var #f) 1 0))
+
+(define (blodwen-system cmd)
+  (fxarithmetic-shift-right (shell-command cmd) 8))